A national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy National Renewable Energy Laboratory Innovation for Our Energy Future Cost-Benefit Analysis of Conference Paper NREL/CP-540-40485 Plug-In Hybrid Electric November 2006 Vehicle Technology A. Simpson Presented at the 22nd International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium and Exhibition (EVS-22) Yokohama, Japan October 23–28, 2006 NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 NOTICE The submitted manuscript has been offered by an employee of the Midwest Research Institute (MRI), a contractor of the US Government under Contract No. DE-AC36-99GO10337. Accordingly, the US Government and MRI retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. 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Available electronically at http://www.osti.gov/bridge Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: mailto:[email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste COST-BENEFIT ANALYSIS OF PLUG-IN HYBRID ELECTRIC VEHICLE TECHNOLOGY1 ANDREW SIMPSON National Renewable Energy Laboratory Abstract Plug-in hybrid-electric vehicles (PHEVs) have emerged as a promising technology that uses electricity to displace petroleum consumption in the vehicle fleet. However, there is a very broad spectrum of PHEV designs with greatly-varying costs and benefits. In particular, battery costs, fuel costs, vehicle performance attributes and driving habits greatly-influence the relative value of PHEVs. This paper presents a comparison of the costs (vehicle purchase costs and energy costs) and benefits (reduced petroleum consumption) of PHEVs relative to hybrid-electric and conventional vehicles. A detailed simulation model is used to predict petroleum reductions and costs of PHEV designs compared to a baseline midsize sedan. Two powertrain technology scenarios are considered to explore the near-term and long-term prospects of PHEVs. The analysis finds that petroleum reductions exceeding 45% per- vehicle can be achieved by PHEVs equipped with 20 mi (32 km) or more of energy storage. However, the long-term incremental costs of these vehicles are projected to exceed US$8,000, with near-term costs being significantly higher. A simple economic analysis is used to show that high petroleum prices and low battery costs are needed to make a compelling business case for PHEVs in the absence of other incentives. However, the large petroleum reduction potential of PHEVs provides strong justification for governmental support to accelerate the deployment of PHEV technology. Keywords: Plug-in Hybrid; Hybrid-Electric Vehicles; Battery, Secondary Battery; Modeling, Simulation; Energy Security. 1 Introduction to Plug-In Hybrid-Electric Vehicles Plug-in hybrid-electric vehicles have recently emerged as a promising alternative that uses electricity to displace a significant fraction of fleet petroleum consumption [1]. A plug-in hybrid-electric vehicle (PHEV) is a hybrid-electric vehicle (HEV) with the ability to recharge its electrochemical energy storage with electricity from an off-board source (such as the electric utility grid). The vehicle can then drive in a charge-depleting (CD) mode that reduces the system’s state-of-charge (SOC), thereby using electricity to displace liquid fuel that would otherwise have been consumed. This liquid fuel is typically petroleum (gasoline or diesel), although PHEVs can also use alternatives such as biofuels or hydrogen. PHEV batteries typically have larger capacity than those in HEVs so as to increase the potential for petroleum displacement. 1.1 Plug-In Hybrid-Electric Vehicle Terminology Plug-in hybrid-electric vehicles are characterized by a “PHEVx” notation, where “x” typically denotes the vehicle’s all-electric range (AER) – defined as the distance in miles that a fully charged PHEV can drive before needing to operate its engine. The California Air Resources Board (CARB) uses the standard Urban Dynamometer Driving Schedule (UDDS) to measure the AER of PHEVs and provide a fair comparison between vehicles [2]. By this definition, a PHEV20 can drive 20 mi (32 km) all- electrically on the test cycle before the first engine turn-on. However, this all-electric definition fails 1 This work has been authored by an employee or employees of the Midwest Research Institute under Contract No. DE-AC36-99GO10337 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes. 1 to account for PHEVs that might continue to operate in CD-mode after the first engine turn-on. Therefore, the author uses a definition of PHEVx that is more appropriately related to petroleum displacement. By this definition, a PHEV20 contains enough useable energy storage in its battery to displace 20 mi (32 km) of petroleum consumption on the standard test cycle. Note that this definition does not imply all-electric capability since the vehicle operation will ultimately be determined by component power ratings and their control strategy, as well as the actual in-use driving cycle. 1.2 The Potential of Plug-In Hybrid-Electric Vehicles The potential for PHEVs to displace fleet petroleum consumption derives from several factors. First, PHEVs are potentially well-matched to motorists’ driving habits – in particular, the distribution of distances traveled each day. Based on prototypes from the last decade, PHEVs typically fall in the PHEV10-60 range [3]. Figure 1 shows the US vehicle daily mileage distribution based on data collected in the 1995 National Personal Transportation Survey (NPTS) [4]. Clearly, the majority of daily mileages are relatively short, with 50% of days being less than 30 mi (48 km). Figure 1 also shows the Utility Factor (UF) curve for the 1995 NPTS data. Daily Mileage Distribution and Utility Factor Curve For a certain distance D, the 100 Daily mileage distribution Utility Factor is the fraction of 90 total vehicle-miles-traveled Utility Factor curve (VMT) that occurs within the first 80 D miles of daily travel. For a 70 distance of 30 mi (48 km), the utility factor is approximately 60 40%. This means that an all- 50 electric PHEV30 can displace 40 petroleum consumption Probability (%) equivalent to 40% of VMT, 30 (assuming the vehicle is fully 20 recharged each day). Similarly, an all-electric PHEV60 can 10 displace about 60%. This low- 0 0 20 40 60 80 100 daily-mileage characteristic is Daily Mileage (mi) why PHEVs have potential to displace a large fraction of per- Figure 1: Daily mileage distribution for US motorists based on vehicle petroleum consumption. the 1995 National Personal Transportation Survey However, for PHEVs to displace fleet petroleum consumption, they must penetrate the market and extrapolate these savings to the fleet level. A second factor that is encouraging for PHEVs is the success of HEVs in the market. Global hybrid vehicle production is currently several hundred thousand units per annum [5]. Because of this, electric machines and high-power storage batteries are rapidly approaching maturity with major improvements in performance and cost having been achieved. Although HEV components are not optimized for PHEV applications, they do provide a platform from which HEV component suppliers can develop a range of PHEV components. Finally, PHEVs are very marketable in that they combine the beneficial attributes of HEVs and battery electric vehicles (BEVs) while mitigating their disadvantages. Production HEVs achieve high fuel economy, but they are still designed for petroleum fuels and do not enable fuel substitution/flexibility. PHEVs, however, are true fuel-flexible vehicles that can run on petroleum or electrical energy. BEVs do not require any petroleum, but are constrained by battery technologies resulting in limited driving ranges, significant battery costs and lengthy recharging times. PHEVs have a smaller battery which mitigates battery cost and recharging time while the onboard petroleum fuel tank provides driving range equivalent to conventional and hybrid vehicles. This combination of attributes is building a strong demand for PHEVs, as evidenced by the recently launched Plug-In Partners Campaign [6]. 2 PHEVs have the potential to come to market, penetrate the fleet, and achieve meaningful petroleum displacement relatively quickly. Few competing technologies offer this potential combined rate and timing of reduction in fleet petroleum consumption [7]. However, PHEV technology is not without its challenges.